1. Field of the Invention
The present invention pertains to methods and apparatus for mixing and dispensing a multi-component cement, such as bone cement, for injection into a body.
2. Background of the Invention
Joints and bones in the human body are often subject to degeneration as a result of disease or trauma. One way of treating this degeneration is to replace the joints or bones using artificial materials. Bone cements play a critical role in this process by acting to anchor implants into place or otherwise help in restructuring degenerated joints and bones.
Bone cements are usually comprised of a liquid monomer component that polymerizes about a polymeric powder component. Typically, the liquid monomer and powdered polymer are mixed just prior to using the bone cement because the mixed cement tends to cure rapidly. During the mixing process, the liquid monomer and powdered polymer react exothermically (i.e., producing heat) and create malodorous vapors. It is desirable for the user to minimize exposure to the vapors and also to ensure that the cement is thoroughly mixed and able to be delivered quickly. In addition, precise control of the cement flow from the device is highly desirable, as it is critical to inject the proper amount of cement, and to make the injection when the cement has the proper consistency.
Various devices have been presented for the mixing and dispensing of bone cement. By way of example, U.S. Pat. No. 6,033,105 discloses an open-ended system where the cement ingredients are mixed in a container using hand-turned mixing blades. After mixing, the cement is delivered to a body location by activation of a corkscrew device that is part of the mixing mechanism. U.S. Pat. No. 6,079,868 teaches mixing and delivery of two ingredients by extruding the ingredients through a static mixing chamber. U.S. Pat. No. 6,286,670 discloses a single vessel for storing a liquid monomer and a solid polymer isolated by a barrier, which may be removed or broken for combining the ingredients to form the cement. U.S. Pat. No. 6,406,175 discloses a mixing and delivery device that is pre-packed with a polymer powder, wherein a user injects the liquid monomer into the device just prior to use. The above-referenced patents are incorporated herein for all that they teach and disclose.